Particulate detergent compositions comprise detersive active ingredients. Often-times these detersive ingredients make the particles ‘sticky’. This has the effect of making the particles stick together which negatively impacts the flowability of the granular composition and can affect the dissolution in the wash liquor. Therefore, a ‘bulking agent’ in the form of a separate particle or powder is often added to the granular composition to counteract the stickiness and maintain good flowability.
Bulking agents include, sulphates, carbonates, silicates, clays (such as bentonite clay), and zeolite. However, carbonates and silicates affect the pH of the wash liquor, making it alkaline and so affecting the cleaning performance of the detergent components. Zeolite is a detergent builder and so interacts with ions in the water that are the source of water hardness. Thus it forms residues of these complexes that deposit on fabrics. Clays result in fabric greying, fabric colour fading and residue deposition on the fabrics.
The most preferred bulking agent is sulphate, as this is pH neutral, and does not act as a builder. However, natural sulphate has a high bulk density so upon addition to water it rapidly sinks and forms a sediment at the bottom of the container. Consumers associate this sedimentation with ‘poor cleaning’ as they believe that the composition is not dissolving into the water and so ‘not working’. Furthermore, in a fabric hand washing context, the slowly dissolving sediment makes the wash liquor feel ‘gritty’. Consumers associate this with ‘dirty wash water’ and ‘lack of cleaning’. In addition, as the sulphate sediments in the wash liquor, it can trap other detergent components and so affect the overall cleaning performance.
Thus, there is a need in the art for a granular laundry detergent composition that at least in part overcomes the above mentioned problems but still exhibits excellent flowability.
The Inventors have surprisingly found that a spray-dried powder comprising (i) from 20 to 80 wt % of a first spray-dried particle comprising less than 5 wt % sulphate, anionic detersive surfactant, and having a bulk density of from 300 g/l to 450 g/l: and (ii) from 20 to 80 wt % of a second spray-dried particle comprising at least 45 wt % sulphate, and having a bulk density of from 350 g/l to 700 g/l overcame this issue. It was further surprisingly found that providing the sulphate in a second particle according to the present invention improved the ability to formulate the sulphate into the spray-dried powder during manufacture.